Under Lake Shore Drive at Lawrence and Wilson avenues, the sky is falling.

Chunks of concrete have broken off the two 1933-vintage bridges, posing a threat to drivers, pedestrians and the dozens of homeless people who camp underneath. Pieces more than 6 inches wide litter the sidewalks. Lattices of rusty rebar are exposed where parts of the wall have broken away.

"The bridge is falling apart real bad," said Thomas Gordon, 58, who lives in a tent on Lawrence. He said he thinks this winter's heavy rains have sped up the deterioration, and people are moving their tents from the worst spots. "We don't want no one to get hurt down here."

The bridges at Lawrence and Wilson are among the most-traveled structurally deficient bridges in Illinois, according to a recent study by the American Road & Transportation Builders Association, a Washington-based trade group which used Federal Highway Administration figures. Nine of the top 10 are in the Chicago area.

Bridge safety came into the national spotlight in August 2007 with the deadly collapse of a Minneapolis bridge that sent cars into the Mississippi River.

The term "structurally deficient" does not mean a bridge is about to fall down, but indicates one in need of repair or rebuilding, said Alison Black, chief economist for the Builders Association. Further deterioration could mean a bridge must be limited to certain load levels or closed.

Most of the state-controlled, structurally deficient bridges on the most-traveled list are in the planning stages for repair or replacement over the next six years, according to the Illinois Department of Transportation. The city of Chicago's transportation department plans to repair three Lake Shore Drive bridges on the list later this year.

But IDOT secretary Randy Blankenhorn and other transportation officials say long-term funding is needed to prevent future problems. The state has been without a capital plan since 2009, and future cash from the federal government is uncertain.

"The secretary has said repeatedly that it would be beneficial for Illinois to have long-term, sustainable funding to protect an asset that separates Illinois from other states — our infrastructure," said transportation department spokesman Guy Tridgell.

The association's study found that 8.4 percent of Illinois' 26,704 bridges are structurally deficient, which means that one or more key elements — such as the bridge deck or its foundation — is in "poor" or worse condition, according to federal standards. Illinois, which has the third-highest number of bridges in the country after Texas and Ohio, ranks sixth in number of structurally deficient bridges and 26th for percentage of such bridges, the report found. Illinois' percentage is below the national average of 9.1 percent.

A bridge on the north side of Chicago at Lawrence Avenue over Lake Shore Drive is crumbling and structurally deficient. (Mary Wisniewski/Chicago Tribune)

A bridge on the north side of Chicago at Lawrence Avenue over Lake Shore Drive is crumbling and structurally deficient. (Mary Wisniewski/Chicago Tribune)

For Chicago bridges on Illinois' top 10 list, the city's transportation department plans repairs to the bridges at Wilson and Lawrence this summer, including structural repair of the concrete, said spokesman Mike Claffey. He said work would take about six to eight months, and the tent community would have to move before it starts.

The city also plans repair of the Lake Shore Drive bridge over the main branch of the Chicago River this summer as part of the Navy Pier Flyover project. This is expected to take about 18 months. The bridge also was on the top10 list for structural deficiency.

Among the state bridges on the list, repairs are being planned and construction could begin on I-290 over Salt Creek in Addison as early as 2018; on I-55 at Lemont and Joliet roads in Will County in 2019; and on I-53 over Kirchoff Road in Rolling Meadows in 2021. The repairs will be paid for with expected state and federal funds, though the funding amounts are not yet known because planning is still ongoing, Tridgell said. Mike Sturino, CEO of the Illinois Road and Transportation Builders Association, said he thought the state had a "good handle" on which bridges needed the most attention. The association is the state chapter of the group that did the bridge report and had been a proponent of the "lockbox amendment" passed last fall that requires all transportation taxes and fees to be spent exclusively on transportation projects.

"If there is a true emergency, they'll shut the bridge down — and they've done that," Sturino said.

He said that more bridges have load limits downstate, which can affect prices, since heavy vehicles must find other routes.

"We have a greater cost ultimately to consumers when they can't use a bridge," he said.

President Donald Trump last week called on Congress to pass legislation for a $1 trillion infrastructure project financed by both public and private capital.

"Crumbling infrastructure will be replaced with new roads, bridges, tunnels, airports and railways, gleaming across our very, very beautiful land," Trump said to a joint session of Congress.

The administration has offered few details on how this would be done, so it's unknown how soon and how much more money could come from Washington. It is also unknown how much could be in the form of direct grants or low-interest loans, as opposed to tax credits for private investors who finance projects.

Democratic legislators have cautioned that private investors are unlikely to be interested in projects like rural roads and untolled bridges, which do not provide a revenue stream. Republican legislators are reluctant to support spending increases not offset by cuts.

Meanwhile, environmentalists warn that climate change can accelerate the problem of decaying infrastructure, since new weather conditions can put added stresses on structures not designed to handle those.

Locally, Illinois has gone 20 months without an operating budget, a problem that must be solved before it can get a new capital program, said Laurence Msall, president of the Civic Federation, a nonpartisan watchdog group. He said the bridge report provides "another reminder for why the state needs a balanced budget enacted as soon as possible."

Ride-share lawsuit

Chicago's Uber and Lyft drivers last week asked to join in a federal lawsuit challenging the city's ban on ride-share advertising.

City ordinance forbids commercial ads inside or outside ride-share vehicles, but allows them in and on taxis. The drivers, who hope to make extra cash from ads, claim the law violates their constitutional rights to free speech and equal protection, according to their motion to intervene.

Vugo, a Minneapolis technology company, had sued the city over the ban last month. Vugo wants to expand its digital advertising business to ride-sharing vehicles here.

The drivers seek the right to sue, an injunction on the ban and a $1 award, said their lawyer, Bryant Greening. The motion will be heard in court next Monday.

Metra survey on fare options

Metra likes surveys.

In January, the commuter rail service was asking about bad customer behavior.

Last week, Metra launched a new survey to ask both customers and nonriders what they think about a variety of potential fare and ticket options, including off-peak and reverse-commute pricing, one-day and seven-day passes, loyalty programs and other ideas.

The survey is part of a study that Metra commissioned last year to evaluate the agency's distance-based fare structure and fare products and to recommend changes, the agency said.

The survey is available at metrarail.com and will be online through March 31. The study should be completed by this summer.